The titanuim labret stud is the perfect flat back stud wich you can leave in place and just change the end with a variety of toppers to mix and match your ear look. 
 
 
With pure titanium, there is no mixed cheap metals involved that can cause reactions. Titanium is regualrly used for surgical implants such as hips and knees, screws and plates. 
Titanium is a high quality metal that carries an extreamly low reaction risk